1. Field of the Invention
The present invention relates to antenna devices preferably for use in HF band communication systems, for example, and to electronic appliances.
2. Description of the Related Art
It is known that by arranging a coil antenna on a planar conductor, the planar conductor comes to have a function of collecting magnetic flux generated by a communication partner on the coil antenna and a function of radiating magnetic flux generated by the coil antenna. Furthermore, it has been disclosed that by arranging a plurality of coil antennas on a planar conductor, magnetic flux is efficiently guided to the coil antennas.
In a system that uses a HF band as communication frequencies, coil antennas are used in antenna devices and communication is performed in a state where the coil antennas are magnetically coupled with each other. Consequently, it is important to increase the coupling coefficient of the coil antennas in order to increase the communication performance.
However, there are cases where it is not possible to increase the coupling between a coil antenna and a communication antenna by simply arranging a plurality of coil antennas on a planar conductor as described in International Publication No. 2012/033031.